Note he's not disputing the actual bodycount. He's saying they weren't authentically Jewish because of the genetic impurities arising through intermarriage with the goyim. His definition of Jewishness is entirely genetic, not creedal.The claims he made have been denounced by various other Jews. But note they don't insist the victims were authentically Jewish because of their beliefs or practices; they simply dispute the extent of intermarriage. In other words, their definition of Jewishness is entirely genetic too.
Rabbi Yosef Mizrahi is involved in Jewish outreach to return Jews to religious life and holds a series of weekly lectures in New York as well as speaking in other parts of the US and has a Facebook page with 77,000 followers.
He also conducts speaking tours in Israel, and has spoken in Ramle, Jerusalem, Afula, Ra’anana, Rehovot, Eilat, Rishon Lezion and Tel Aviv.
Prof. Kimmy Caplan, head of the Department of Jewish History and Contemporary Jewry at Bar-Ilan University said Mizrahi’s claims had no basis in fact and were not backed up by any corroborating data.
“Someone who says this is completely detached from historical reality,” he told The Jerusalem Post.
“There is no historical evidence that sustains such an argument or anything that comes close to such an argument.” Caplan said that intermarriage did occur on a small scale in Germany, France and the UK but noted that neither Jewish newspapers nor rabbinical responsa in Europe, especially Poland and Eastern Europe, discussed the issue of intermarriage before the Holocaust because, he said, the issue did not exist on a large-scale level.
“Jewish society was discussing anti-Semitism, Jewish nationalism, and other issues but there was no discussion of intermarriage because it wasn’t a reality of Jewish life,” he said.
Efraim Zuroff, director of the Simon Wiesenthal Center’s Israel office and a Holocaust historian, described Mizrahi’s comments as “made up history to suit an agenda,” and accused Mizrahi of using his claims to encourage people to be more observant Jews.
“He wants people to be more religious, so he’s saying be religious by downplaying the Holocaust through an attack on the ‘imperfect’ Jewish identity of people who are not religious,” said Zuroff.
“This is a product of the utter ignorance of the actual historical record.” In response to a request for comment from the Post, Mizrahi said he had “never determined this fact” and said that “a group of liars systematically distort my words and take them out of context.”
“At the time of the Holocaust, the Nazis murdered people who were half-Jewish or a quarter- Jewish according to their system – although as I said according to the Torah there is no such thing as half-Jewish but rather that someone is either totally Jewish or totally non-Jewish.
“I explained in my lesson that it is possible that 5 million Jews died or 3 million or even just one million.
“The reason I spoke about the issue was to alert the public to the awful assimilation that is taking place right now in the world.”
According to Prof. Robert Gellately, editor of Social Outsiders in Nazi Germany, in 1935 when the Nuremberg laws were passed, “approximately 35,000 of the 500,000 members of German Jewish communities lived in intermarriages.”Source
Another interesting video from the same rabbi.
On a similar theme, a novel that features a romance between a "Palestinian" man and an Israeli Jewish woman has been banned from use in Israeli schools "on the grounds that it could promote mixing between the two nations and undermine the distinct identity of Israeli Jews". (here)